摘要
Introduction The discovery of cell-free fetal DNA(cff-DNA),also known as noninvasive prenatal testing(NIPT),by Lo et al.in 1997,1 has significantly changed the screening for common chromosomal abnormalities.Its widespread acceptance globally underscores its impact.NIPT analyzes fetal DNA originating from the apoptosis of the outer cytotrophoblast,the fetal hematopoietic system,and lysis of other fetal cells.The DNA fraction increases from 10%to 15%between 10 and 20 gestational weeks.Rapid cff-DNA clearance occurs in maternal circulation,spanning from 4 minutes to 2 weeks postpartum.
